The research, which was conducted among adults with mild cognitive impairment (MCI), offers the opportunity for intervention before more advanced forms of dementia develop, US scientists said.
Study participants with MCI who received the probiotic Lactobacillus rhamnosus GG (LGG) for three months saw their cognitive scores increase. This improvement was also associated with changes in their gut microbiome.
Mashael Aljumaah, a microbiology doctoral candidate at the University of North Carolina at Chapel Hill and North Carolina State University, told Vitafoods Insights: “Probiotics, including the specific strain LGG utilised in our study, have demonstrated potential in slowing age-related cognitive decline through modulation of the gut microbiome's composition.
“Our research identified a correlation between certain gut bacteria, such as Prevotella, and MCI. Through probiotic intervention, we observed a decrease in these specific taxa linked to MCI, leading to improved cognitive scores.
“While the exact mechanisms underlying this connection warrant further study, our findings indeed highlight the gut-brain axis as a critical factor in cognitive health. The results suggest that probiotics might offer a promising avenue to influence this vital connection positively.”
‘Exciting’ findings add new layer to understanding of the brain-gut microbiome
Aljumaah, who is also affiliated with King Saud University in Saudi Arabia, said the implications of the finding were “exciting”, adding “a new layer to our understanding of the microbiome brain-gut connection” and opening up new avenues for intervening at an earlier stage of age-related cognitive decline.
“Many studies focus on severe forms of cognitive diseases, such as Alzheimer's and dementia, but these conditions are more advanced, making them significantly harder to reverse or treat,” she said while presenting the findings at Nutrition 2023, the annual meeting of the American Society for Nutrition. “In contrast, we focused on MCI, which can include problems with memory, language, or judgement.
“Interventions at this stage of cognitive impairment could slow down or prevent the progression to more severe forms of dementia.”
‘Compelling case’ for targeting gut microbiome to support cognitive health
The study involved 169 participants aged 52 to 75 years old who were divided into two groups: those with no neurological issues and those with MCI. They received either the LGG probiotic or a placebo in a double-blind, randomised clinical trial lasting three months.
The researchers used 16S rRNA gene sequencing to identify and compare bacteria present in stool samples, before using whole genome sequencing to gain insights into the functional roles of the bacteria identified.
The analysis revealed that microbes in the genus Prevotella were present in a higher relative abundance in participants with MCI than those with no cognitive impairment, suggesting that gut microbiome composition could serve as an early indicator for MCI.
For study participants who had MCI and received the LGG probiotics, the Prevotella relative abundance decreased. This change coincided with improved cognitive scores, suggesting that cognitive health in older adults could be improved by manipulating the gut microbiota.
Aljumaah said: “Our findings present a compelling case for the feasibility of utilising gut microbiome-targeted strategies, specifically by manipulating the gut's microbial composition, as a fresh avenue to support cognitive health.”
Opportunities for creating specialised products to combat age-related cognitive decline
Asked about the implications for industry, Aljumaah said: “This opens up a new area of opportunity in creating specialised products aimed at cognitive wellbeing. Supplement brands could invest in research and development to formulate products containing strains proven to have a positive impact on cognitive health. Collaborations with scientific communities could further validate these products, and marketing strategies can be developed to educate consumers about the potential benefits.”
However, she sounded a note of caution, adding that it was “essential” for the findings to be replicated in different demographics and regions.
“The promising results observed in our study offer a valuable starting point, but thorough exploration and validation across diverse populations are necessary to fully realise and responsibly promote the potential of this approach,” she added.
Future research to explore molecular pathways involved in gut-brain axis
Aljumaah said future research should aim to understand the precise mechanisms by which probiotics and the gut microbiome influence cognitive function.
She added: “This includes exploring the molecular pathways involved in the gut-brain axis, identifying the specific roles that different bacterial strains play in cognitive health, and further investigating the underlying mechanisms in certain bacteria like Prevotella, on which we are currently conducting a follow-up study to uncover a novel mechanism.
“Moreover, conducting larger, long-term clinical trials will help determine the sustained effects of probiotic intervention. Investigating individualised responses to various probiotic strains could lead to personalised gut microbiome-targeted strategies. The combination of these efforts can forge a path towards more effective and targeted approaches for maintaining and improving cognitive health through the gut microbiome.”